Here’s two free tools from Microsoft that will help you clean and protect your computer.
Microsoft Security Essentials
Microsoft Security Essentials is a free antivirus program for your personal computer, and provides real-time protection against viruses, spyware and other malicious software.
The program runs in the background while you’re using your PC and checks daily for any updates from the Internet. It performs scheduled scans of your computer for any malware, automatically blocking most threats. Basically, if your Microsoft Security Essentials icon is displayed as green in the notification area, at the far right of the taskbar, your computer is in good condition. If the program detects a problem or threat, it displays a message with the detected item, the alert level, and the recommended action, so you can decide how to proceed. You can also use Microsoft Security Essentials to perform a manual scan of a file, a folder, or your entire PC, at any time.
The Microsoft Windows Malicious Software Removal Tool
The Microsoft Windows Malicious Software Removal Tool checks Windows Vista, Windows 7, Windows XP, Windows 2000, and Windows Server 2003 computers for and helps remove infections by specific, prevalent malicious software—including Blaster, Sasser, and Mydoom. When the detection and removal process is complete, the tool displays a report describing the outcome, including which, if any, malicious software was detected and removed.